Robotic Amputee Gait Capacity Assessment System Robotic prostheses can improve mobility for individuals with amputation, but assessment and prescription for each individual is difficult and errors are costly. We propose to determine the feasibility of a product that allows rapid, objective assessment of the functional benefits of various conventional and robotic ankle-foot prostheses in a clinical setting. Our first aim is to demonstrate a system capable of dynamic prosthesis emulation. We have recently developed an experimental robotic test bed with significantly enhanced mechatronic performance. In this project, we will test its suitability for high-level emulation of three classes of prosthesis: conventional (e.g. SACH), dynamic-elastic (e.g. FlexFoot), and robotic (e.g. BiOM), differentiated by the mechanical work absorbed or produced during a step. Our second aim is to develop objective and repeatable measures of the functional benefits to potential users of these devices, specialized for use in coordination with the robotic prosthesis emulator. Finally, we aim to demonstrate that such a system can differentiate between patients who would benefit from advanced robotic prostheses and those who would not. We propose to perform an experiment in which different classes of prosthesis are emulated and functional outcomes are assessed in four amputee subjects with different activity levels and etiologies. These experimental results will help determine which population groups can be expected to benefit from the mechanical work provided by robotic foot-ankle prostheses, and provide insight into measures that systematically differentiate between potential beneficiaries and non-candidates. This research is the first step toward developing a diagnostic product that Orthotics and Prosthetics clinics can use to assess candidates for advanced robotic prostheses and justify reimbursement from insurance carriers on the basis of objective functional benefits. The eventual integrated product will consist of robotic prosthesis emulator hardware and software, with optional experimental tools. This clinical tool will be priced competitively with single autonomous robotic devices, in te same class as robotic gait trainers. More advanced platforms will eventually enable dynamic optimization of device parameters, such as keel length or stiffness, prior to device construction and purchase, and may even lead to the development of improved autonomous designs.